Dispersion Characteristics And Mass Transfer In A Pilot‐Scale Gas‐Liquid Oscillatory‐Plate Column
Published 2012 · Chemistry
Mass transfer and hydrodynamic characteristics of an oscillatory-plate column (OPC) and their relation to energy dissipation were investigated using a 0.1-m diameter pilot-scale unit. The column is characterized by having plates with a small hole diameter (1.6–3.2 mm) oscillating at 180° out of phase at higher frequencies (0–30 Hz) and small amplitudes (0–3.2 mm). Using this design, it was possible to achieve gas holdup and specific interfacial areas as high as ∼0.8 and 400 m–1, respectively. The maximum gas superficial velocity achieved reaches as high as 1.7 m/s, while the axial dispersion coefficient ranged from ∼10–4 to over ∼3 × 10–3 m2s–1, which is almost one order of magnitude lower than that in bubble columns under similar flow rates. The value of gas velocity of ∼0.1 m s–1 seems to mark a transition beyond which interfacial area, holdup, and axial mixing become practically unchanged. Keeping in view its performance characteristics, the column can satisfactorily meet many of the demands posed by intensified wastewater treatment processes, namely high rates of oxygen transfer, multistage operational mode, uniform distribution of small-scale turbulence structure, and the ability to handle sludge with relatively high concentrations of suspended solids.